update.php: Fix PHP4 syntax error

PHP4 does not support method chaining, so I broke the line into
two so we can continue to show a more helpful error message in
that version of PHP, which reached EOL just about six years ago.

Also changed "Done. The job took [...]" to "Done in [...]"; "job"
has a specific meaning in MediaWiki that is irrelevant here.

Follows-up fae8daa658c1.

Change-Id: If2480aa24f18d36f33462d874b2a1dd13abb641a